Research – Pavement Markings

Chapter 2. MUTCD Warrants

Longitudinal pavement markings (center lines, lane lines and edge lines) are a traffic control device and are included in the MUTCD. The MUTCD defines characteristics of pavement markings such as width, pattern, and color. The MUTCD also includes the standards that define when and where pavement markings are used on roadways in the United States.

The 1993 Department of Transportation Appropriations Act directed the FHWA to include warrants for longitudinal pavement markings in the MUTCD. The Markings Technical Committee of the National Committee on Uniform Traffic Control Devices provided FHWA with warrant criteria recommendations based upon available research and engineering judgment for center line and edge line markings. FHWA concluded a series of rulemaking efforts on January 3, 2000, when the final rule modifying the MUTCD was adopted by establishing warrants for center line and edge line longitudinal pavement markings. The warrants are based on traffic volume, functional classification, and roadway width.

Since the pavement marking warrants were added to the MUTCD, several studies have been conducted regarding the safety effect of applying more aggressive criteria than the MUTCD warrants. The most recent study was released in 2013, in which MoDOT investigated the safety effects of striping edge lines on low-volume rural highways (i.e., roadways with annual average daily traffic [AADT] of 400 to 1,000 vehicles per day [vpd]). Prior to this study, MoDOT's policy was to stripe routes with an AADT of 1,000 vpd or greater with both an edge line stripe and a center line, while routes with traffic volume less than 1,000 vpd only had a center line stripe. By adding edge lines to routes with 400 vpd or greater, MoDOT increased the number of miles of fully striped roadways by nearly 7,500 miles.(5)

MoDOT started the additional edge line striping in 2009 and completed it in 2012. One district completed its eligible routes in 2009–the 570 center line miles of highways in that district were used in this study. A total of 576 crashes occurred on these highways from 2006 to 2008. Of these 576 crashes, 105 involved either a fatal or disabling injury crash (35 severe crashes per year). Of the severe crashes, 79 involved the run-off-the-road right crash type. Overall, there were a total of 340 run-off-the-road right crash types in the combined locations.

The after data included years 2010 and 2011. During this two-year span, a total of 327 total crashes occurred, 46 of which involved either a fatal or disabling injury crash (23 severe crashes per year). Of the severe crashes, 31 involved the run-off-the-road right crash type. Overall, there were a total of 173 run-off-the-road right crash types in the combined locations.

Using the empirical Bayes method for analysis, the study showed a 15.2 percent decrease in total crashes for all crash types (significant at the 95 percent confidence level). In addition, severe crashes decreased by 19.3 percent (though this data was not able to gain statistical significance due to the small sample size).

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